Colwell was fined $500,000 and barred from ever serving as an officer or director of a public company. He has agreed to cooperate with the federal investigation into Enron, the SEC said. Colwell consented to the charges without admitting or denying the allegations.

Enron North America was Enron's biggest subsidiary.

According to the SEC, Colwell improperly used Enron North America's reserve accounts in the first six months of 2001 to mask over $1 billion in losses at Enron Energy Services, the company's retail energy business.

In the fourth quarter of 2000, Colwell inflated the value of Enron's largest private asset -- Mariner Energy, an oil and gas company -- so Enron could generate an additional $100 million of earnings to meet Wall Street profit targets.

The SEC further charged that Colwell helped Enron avoid a $1.4 billion loss from its Houston Pipeline asset in the second quarter of 2001 by improperly structuring a leasing transaction with a third party that fudged Enron's cash flows.

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